Wednesday, May 24, 2006

Some of the best blogs are written by professionals that are between jobs, often graduate students in transition. Tetrapod Zoology is one of those blogs. This is an excerpt from a fascinating story ... a world about which I know little ...

... Sad to say, during the Late Triassic, dicynodonts dwindled in diversity until by the Norian (the penultimate stage of the Late Triassic) they were down to just three genera, and all of these were close relatives within the clade Kannemeyeriiformes (King 1990, Maisch 2001). I always liked Richard Cowen’s suggestion that these last forms were ecologically peripheralised, endangered species that hung on to existence in remote ecosystems where life was harsh ... dwindling in numbers, and living in a world where big archosaurs were now controlling all the terrestrial ecosystems, those poor last dicynodonts gradually faded into oblivion, until they were but dust in the wind, dude. That was a Bill and Ted reference.

In June 1915 several fragmentary fossil bones were discovered near Hughenden in Queensland (Australia)... a 2003 reappraisal of the specimens by Tony Thulborn and Susan Turner showed that the bones could not belong to anything other than a dicynodont....

But here’s the big deal: the fossils are from the late Early Cretaceous, and thus something like 100 million years younger than the previously known youngest members of the group... So dicynodonts didn’t disappear in the Late Triassic as we’d always thought. They had in fact been sneakily surviving somewhere, and as Thulborn & Turner (2003) wrote, their persistence in Australia and absence from everywhere else suggests that ‘Australia’s tetrapod fauna may have been as distinctive and anachronistic in the Mesozoic as it is at the present day’ (p. 991)...

We mammals are but the shards of rich group of species that mostly died in the Triassic ...

This is why blogs are great, even though they are transient. Soon Darren will be too busy to put this kind of mini-article together.